Other Polynuclear Compounds

Minabe and Nakada studied the hydrogenation of pyrene over Raney Ni in ethanol at room temperature and atmospheric hydrogen pressure.266 The selectivities to dihydro-, tetrahydro-, and hexahydropyrenes at an initial stage and after 8 h reaction are shown in Table 11.24. 

It is seen that initially 4,5-dihydropyrene (31), 1,2,3,6,7,8-hexhydro(,s-hexahy-dro)pyrene (33), and l,2,3,3a,4,5-hexahydro(a,s -hexahydro)pyrene (34) are formed simultaneously from pyrene. The most part (78%) of initially formed 31 is hydrogenated to the tetrahydro derivative 32 rather rapidly. The hydrogenation of 32 is very slow under these conditions, and it has been shown that it is isomerized largely 

Mochida et al. studied the hydrogenation of fluoranthene (39) over carbon-sup-ported platinum metal catalysts in decalin at elevated temperatures and pressures.267 Fluoranthene was hydrogenated much more readily than pyrene, and was highly selective for the formation of tetrahydrofluoranthene 40 over all the catalysts investi- 

Benz [a] anthracene (44, R = H) gives the 8,9,10,11-tetrahydro derivative 45 when hydrogenated over Adams platinum in ethanol in the presence of ferrous chloride and hydrochloric acid. There was no indication that the 7,12-dihydro derivative, the alcoholysis product of the disodium compound, was an intermediate leading to 45. The 

The reactivities and selectivities of various polynuclear carbocyclic and iV-hetero-cyclic aromatic compounds in the hydrogenation over transition metals have been discussed by Sakanishi et al.264 and Minabe et al.261 

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Beside organic polymers, metallocyanates and other polynuclear compounds can also be deposited. 

Whenever unvented combustion occurs iadoors or when venting systems attached to combustion units malfunction, a variety of combustion products win be released to the iadoor environment. Iadoor combustioa units include nonelectric stoves and ovens, furnaces, hot water heaters, space heaters, and wood-burning fireplaces or stoves. Products of combustion include CO, NO, NO2, fine particles, aldehydes, polynuclear aromatics, and other organic compounds. Especially dangerous sources are unvented gas and kerosene [8008-20-6] space heaters which discharge pollutants directly into the living space. The best way to prevent the accumulation of combustion products indoors is to make sure all units are properly vented and properly maintained. 

Other polynuclear hydrocarbons may include bridged hydrocarbons, spiro hydrocarbons, mixed systems containing alicyclic and aromatic rings, and aliphatic chains, etc. Examples may be found in the CRC Handbook [63, Section C]. Physical properties of selected polynuclear aromatic compounds are given in [49, p. 967]. 

Phenanthrene, anthracene, and other polynuclear aromatic compounds. 

Polynuclear compounds containing other bridging groups are described under the cobalt-ammines. 

Alkylbenzenes and other activated aromatics, such as polynuclear compounds, may react without a catalyst. Halogenation, in this case, occurs with the involve-ment of molecular halogens. Polarization of chlorine and bromine molecules is brought about by their interaction with the aromatic ring. For example, bromination in the presence of acetic acid is suggested to take place through the transition state 5, leading to the formation of the a complex ... 

Reduction of other polynuclear aromatics can similarly be controlled to yield different products. Although the site of reduction is difficult to predict, the first step in reduction of such simple compounds as phenanthrene and anthracene occurs... 

Many chemicals are metabolized to carcinogens by processes that do not seem to involve free radicals a well-understood example is the oxidation of benzo(a)pyrene [B(a)P] to the diol epoxide by the cytochrome P450 system. However, the oxidation of B(a)P and other polynuclear aromatic hydrocarbons (PAH) to carcinogenic compounds can involve radicals. This statement, while once controversial, now has ample evidence (12.,22,25.). Although it is clear that some products arise from radical-mediated metabolism of PAH, the involvement of these products in tumorigenesis is less clear nevertheless, I believe that such evidence does now exist (12,12). 

The compound Na2 [Rh12(CO)30] can be prepared by reaction of Rh2(CO)4-Cl2 with sodium acetate in methanol under an atmosphere of carbon monoxide.1 It contains one of the fust polynuclear anions to be formed when the rhodium carbonyls or carbonyl halides are reduced by the action of alkaline reagents in alcohols or by alkali metals in tetrahydrofuran (THF). It provides a unique example of a double octahedral cluster carbonyl anion in which the noble gas rule is not obeyed,1 2 and it is a starting material for the preparation of other polynuclear rhodium carbonyl anions.1 3"5 The synthesis reported here is a modification of the original method. The starting material is Rh4(CO)i2, now easily prepared at atmospheric pressure.6"8 The reaction is fast, and the overall procedure requires about 6-7 hours with 80-85% yields. 

Our results on the reductive alkylation of coal offer insights into proposed analogies between coal chemistry and graphite chemistry (37). Graphite, as the largest polynuclear aromatic compound, can be reduced by anions of all other polynuclear aromatic compounds in fact, this observation has been exploited to synthesize intercalation compounds (38j. Although the added electron density of these compounds is predominantly on the carbon planes, these infinite aromatic anions possess chemistry distinct from that of molecular-basis aromatic anions. While napthalene anion will react with water to form a mixture of 1,4-dihydro-naphthalene and naphthalene, the graphite anion is inert to water (39-42) ... 

Capillary electrophoresis has been used for the analysis of chiral pollutants, e.g., pesticides, polynuclear-aromatic hydrocarbons, amines, carbonyl compounds, surfactants, dyes, and other toxic compounds. Moreover, CE has also been utilized to separate the structural isomers of various... 

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